Machines for grinding gear tooth and like profiles



May 27, 1958 'r. E. CALDERWOOD 2,335,014

I HACHINES FOR GRINDING GEAR TOQTH AND LIKE PROFILES Filed June 18, 19532 Sheets-Sheet 1 Y X A Q1/1420. J I M 1 I vK z/ wum . m I l um mu NW y1953 T. E. CALDERWOQD 2,836,014

MACHINES FUR GRINDING GEAR TOOTH AND LIKE PROFILES Filed June 18, 1953 2Sheets-Sheet 2 r I. V. 22% mm Y X A. a

PAACHEIEE FOR GRINDING GEAR TOOTH AND LIKE PROFILES Thomas EthelredCalderwood, Staines, England, assignor to W. E. Sykes Limited, Staines,England Application dune 18, 1953, Serial No. 362,451

Claims priority, application Great Britain June 18, 1952 9 Claims. (Cl.51-45) This invention relates to machines for grinding gear tooth andlike profiles of the kind comprising a grinding wheel having a spirallyribbed periphery which has a profile corresponding to the rack form orequivalent profile of the tooth pitch desired, the required profilebeing generated by rotating the wheel and work in the required relationwhilst effecting a relative movement between the grinding wheel and thework in the general direction of the axis of the work. More particularlythe invention is concerned with improved means in a machine of this kindfor imparting simultaneous and co-ordinated relative motions to thegrinding wheel and the work such that in addition to rotation of thegrinding wheel and work about their respective axes, and relativemovement of the grinding wheel and the work in the direction of the axesof rotation of the work there is also afforded a coordinated relativemovement between the axes of rotation of the grindin wheel and workrespectively for increasing and/ or decreasing the distance between thesaid axes.

It is the object of the present invention to provide a simple andeffective arrangement of a machine for the above mentioned purposewhereby gear tooth and like profiles, particularly of a barrel or othertapered or curved form, can be ground.

In accordance with the invention therefore there is provided a machineof the kind referred to for grinding gear tooth and like profiles havingmeans for imparting simultaneous and co-ordinated relative motions tothe grinding wheel and the work to cause rotation of the grinding wheeland the work about their respective axes and relative movement of thegrinding wheel and the work in the direction of the axis of rotation ofthe work and including a crank or other member which is rotatable tocause reciprocation of a rack meshing with a pinion which is therebyrotatable to afford by means such as a threaded rod and nut aco-ordinated relative movement between the axes of rotation of thegrinding wheel and the work respectively for increasing and diminishingthe distance between the said axes. In a preferred machine the pinion isarranged to impart the required movement to a slide carrying thegrinding wheel, this motion being co-ordinated with the motion of thework-piece.

Figures 1, 2 and 3 are diagrammatic end elevations of three involutegears having the same tooth characteristics but of ditfereut outsidediameters;

Figure 4 is a side view, more or less diagrammatic, of a laminated gearof conical form;

Figure 5 is an end view of such a gear;

Figure 6 is a side view of a laminated gear similar to that of Figure 4,in which the laminations are relatively displaced angularly to form ahelical gear;

Figure 7 is a sectional elevation of a machine constructed in accordancewith the invention for grinding gear tooth and like profiles;

Figure 8 is an elevation of the grinding wheel;

Figure 9 is a part longitudinal section of the wheel;

Figure 10 is an end view of Figure 7.

States Patent ,7 2,836,014 Patented May 27, 1958 It is known thatinvolute gears having the same number of teeth, the same base circlediameter, and having a gear tooth form which can be enclosed in the samerack tooth form, can be generated to have different outside diameters.diagrammatically in Figures 1, 2 and 3. The involute form of each gearis constructed on the same base circle D and in each case the gear toothis based on the same rack tooth form A. The outside diameter D of thegear shown in Figure 1 is greater than the outside diameter D of thegear shown in Figure 2, and the outside diameter D of the gear shown inFigure 3 is less than D if a number of gears are produced as thinlaminae having their outside diameters varying progressively from D to Dand these are assembled in their progression of diameters with the axesof symmetry of the gear teeth in line, a gear will be produced as showndiagrammatically in Figures 4 and 5 having an outside diameter ofconical form, a constant cylindn'cal base circle diameter, and the samerack tooth form equivalent at any diameter of the conical form. Also, ifthe axes of symmetry of the gear teeth of successive laminae are givenan angular dis placement, a helical gear of conical outside form will beproduced as shown in Figure 6. Gears of this form have numerous uses,particularly for use as gear shaper cutter, and this invention isconcerned with means for forming such gears or cutters by the generatingprinciple.

The invention will be described as applied by way of example to a geargrinding machine having a grinding wheel of the form shown in Figures 8and 9. This wheel is of generally cylindrical shape having an axis 1 andhaving formed on its periphery a helical thread or worm 2, the crosssection 3 of which is constant and corresponds to the rack form of thetooth pitch it is desired to generate. The grinding wheel, showngenerally at 4 in Figures 7 and 10, is mounted on a shaft 5 carried inbearings 6 secured to a slide 7 which can be displaced in a slideway onguides 8 formed in a table 9 which is supported from a main framestructure 10. A worm wheel 11 secured to the grinding wheel shaft isdriven by a worm 12 on a shaft 13 rotatable in a bearing 14 on the slide7. The shaft 13 is formed with splines 15 and is slidable within anddriven by a splined sleeve 16 rotatably mounted in a bearing 17 on thetable 9. A bevel gear 13 integral with the sleeve 16 meshes with a bevelgear 19 secured to a vertical shaft 20 which is driven by bevel gears 21from a horizontal shaft 22 driven by a belt 23 and pulleys from anelectric motor 24 or other convenient source of power. The splined shaft15 slidable in the driving sleeve 16 permits the grinding wheel to berotated while the slide 7 which carries it can be moved at a slow speedalong the slideway 3. For displacing the slide 7, a lug 25 extendsdownwardly from the slide and has threaded engagement with a threadedshaft or screw 26 mounted inbearings on the table 9. A gear wheel 27 issecured to the shaft 26. l

The work gear 28 is mounted upon a spindle 29 held between centres 39and 31 mounted in brackets 32 and 33 on a slide 34 movable in slideways35 which are formed in a head 36 mounted for angular adjustment about ahorizontal axis. For this purpose the rear of the head is formed with aspigot portion 37 surrounded by a flange 38 which fits within a socketrecess 39 with the flange bearing against a circular slide surface 40.The socket recess is formed in the side of a hollow column '41 whichrises from the main frame structure 10. Any

in a bracket 43 on the head 36 and having threaded 'en- Examples ofthree such gears are shown.

' gagernent with the slide.

meshes with a gear 45 which through a clutch 45a drives a shaft 46rotatably mounted in the head and driven by a bevel gear 47 meshing witha bevel gear 48 on a sleeve 49 rotatably mounted in the head 36 andaligned with the axis of angular adjustment of the latter. The sleeve 49is integral'with a second bevel gear 50 meshing with a bevel gear 51 ona vertical shaft 52 carried in bearings 53 secured to the hollow column41. p

Rotation of the work gear 28 is effected by a carrier 54 secured to thework spindle 29 and engaged by a collar 55 secured to the centre spindlewhich is driven by meshing gears 56from a shaft 57, all mounted in theslide 34. The shaft 57 has a splin ed portion 58 slidably engaged inasplined sleeve 59 rotatably mounted in the head 36 and formed integralwith a bevel gear 60 which meshes with a bevel gear 61 on a horizontalshaft 62. The shaft 62 g is concentric with the aXis'of angularadjustment of the head 36 andextends freely through the previouslymentioned sleeve 49.

The shaft 22'driven by the motor 24 has secured to it a gear annulus 63of a differential gear including a second gear annulus 64 secured to ashaft 65 coaxial with shaft 22 and planet gears 66 on a rotatablecarrier 67. The shaft 65 drives through change gears 68 a shaft .69which is connected by bevel gears 70 to a vertical shaft 71 driving theshaft 62 through bevel gears 72 and thereby rotates the work gear 28through .the gearing. previously described. The change gears'68 areselected in accordance with the number of teeth required in the workgear and the number of starts of the helical or screw A gear 44 on theshaft 42' crank disc will cause the rack 104 to be reciprocatedvertically thereby giving reciprocating angular motion to the pinion107. The clutch 111 being engaged with pinion 107 reciprocating angularmotion will be given to shaft 110 and by the gears 84 .and 2'7 to screw26.

The amount of barrelling can be chosen by: a (a) The setting for thethrow of the crank pin 103; (b) The choice of change gears 101'and 75thus determining the angular movement of the crank disc 103 for anytravel of the slide 34 along the guide ways 35.

F or the production of work with a taper-root diameter clutchlll is'engaged with pinion 109 when the screw 26 is given rotation in onedirection only. .1 7

Change gears 101and 75 can be selected to give any number of revolutionsof the screw 26 in one direction, either clockwise or anti-clockwise forany movement of the slide 34 along the guide.ways 35.

. The machine may be set by hand in correct cry-relation of movements byturning shaft 76 by the square end 94 provided or by turning thesha ft110 by its'square end 113 with clutches 93, 45a and 111 engaged ordisengaged as required.

The horizontal slow speed shaft 76 is also connected 4 through bevelgears 85 to a shaft 36 and thence through to the carrier 67 of thedifferential gear. Worm wheel 91.

form of the grinding wheel 4. The vertical shaft 71 also 7 drives ashaft 73 through bevel gears 74 and thence through change gears 75 andthe drive is transmitted to a slow speed horizontal shaft 76. Bevelgears 77 connect the horizontal shaft 76 to the vertical shaft 52 whichdrives the screw 42 controlling the slide 34, as previously described.By this means the slide 34 is slowly traversed in its slideway. Thehorizontal shaft 76,

is also connected to the gear 100 through change gears 101. The gear 100is keyed to the shaft 102 as is also the crank disc 103. A rack member104 is mounted in a slide 105 which slide is fixed to the main structure10. The rack member is formed with a T head in which is formed a slot106. The teeth of the rack engage the pinion 107. A crank pin 108adjustably mounted in a T slot on the face of the crank disc 103 engagesthe slot 106 so that rotation of the crank disc 103 causes the rack 104to move vertically in its slide 105 and so imparts a reciprocatingangular motion to the 'pinion 107 the.

amount of such reciprocation being dependent on the angular movement ofthe crank disc 103 and the distance of the crank pin 108 from the centreof the crank disc. Thus, referring to Figure 10, if the crank discrevolves clockwise the rack will rise vertically until the crank pin 108arrives at the top dead centre of the crank disc 103.

After passing the top dead centre the crank pin will cause the rack tofall vertically. The gear 100 drives the pinion 109. Both the pinion 109and the pinion 107 can revolve freely on the shaft 110 and both areprovided with fine clutch teeth to engage the clutch 111 which isslidably key-mounted on shaft 110.

Appropriate movement of clutch 111 will cause either the pinion 107 orthe pinion 109 to be connected to shaft 110. Shaft 110 drives'the screw26 through gears 84 and '27. By this means the slide 7 carrying thegrinding wheel 4 is given motion either towards or away from the workgear 28 dependent on the rotation of the screw 26. v V 7 When shaft 76revolves, the crank disc 103 revolves,

7 being driven by the appropriate change gears 101 and the gear 100through the shaft'102 carrying the crank disc 103. As before described,the passage of the crank pinj 9W? fd angawavimm: the. t p. dea ntre. f.he

change gears 87 and bevel gears 88 to a shaft'89 carrying a worm 90meshing with a worm wheel 91. A worm 91a meshes witha worm Wheel ring 92formed on or secured and worm 91a are both mounted on and keyed to ashaft 91b. This differential gear and its connection with the horizontalshaft 76 is'only employed when generating helical gear tooth forms. Whenproducing "straight or spur gear forms, the differential gear isdisconnected, for. example by removing the change speed gears 87 so thatthe planet pinion carrier 67 is locked by its engagement with the worm91'and the two shafts 22 and 65 revolve at thesame speed,

The drive of the horizontal shaft 76 from'the change.

speed gears 75 can'be controlled by a clutch indicated at 93 on shaft73. By disengagingthis clutch, the shaft 76 a can be rotated by hand byapplying a key to its squared end 94. In a similar manner, by handrotation of the g ing wheel slide 7 are initially set-so that the slide34 can be slowly traversed past the wheel for the generating of therequired tooth form, the speed of traverse being prede-- terminedbysuitable choice of the change speed gears 75. It is necessary that the.rotation of the work gear should M be suitably coordinated with thespeed of rotation of the spirally ribbed grinding wheel, and this ispredetermined by an appropriate choice of the change speed gears 68. Thegrinding wheel is also" given a slow movement either towards or awayfrom the work gear according to the direction of naversexof the, slide34, to give the work the desired conical-or tapered form, the amount oftaper being predetermined by a suitable choice of the change speed gearsand 101. In Figure 7 the grinding Wheel is shown in a withdrawn positionhalfway between the end diameters D and D (Figures 4 to 6) of the workgear. It will be clear that if the work is traversed down-. wardly, thegrinding wheel slide must be moved inwardly at the same time to producethe desired taper frem D 10D;- 1 7 V V f i I When it is desired togenerate helical gear forms, the

' head 36 is adjusted in its spigot mounting to the required inclinationwith respect to the line of the helix of the grinding wheel and thehelix of the work gear. The necessary additional rotation of the workgear is afiorded by the difierential gear which is driven throughsuitably chosen change speed gears 87. By this means the central planetpinion carrier 67 of the differential gear is revolved at a slow speedand additional motion is thereby imparted to the shaft 65 and thence tothe work gear.

It will be understood by those skilled in the art that co-ordinatedmotions may be obtained by other than change gears, and the scope of thepresent invention is not restricted thereto. It is also to be understoodthat relative motion may be obtained between the grinding wheel and gearby other than the specific embodiment illustrated herein and the scopeof the present invention is not restricted thereto.

The invention is not restricted to the production of involute toothforms. It can be applied with particular advantage to the grinding ofgear shaper cutters, which may be of involute or other tooth form. Forexample, cutters for producing sprocket wheels or clutch elements ofgear form may be conveniently and economically generated on machinesaccording to the invention.

claim:

1. In a machine of the type described, a helical-profile grinding tool,means for rotatably supporting said grinding tool, means for rotatablysupporting a workpiece, means for rotatably driving said grinding tooland Workpiece in timed relation, means for reciprocating said grindingtool in a direction perpendicular to the axis of rotation of theworkpiece, and means for moving the workpiece in the direction of itsaxis of rotation in timed relation to the reciprocation of said grindingtool.

2. In a machine of the type described, a motor, a base, a first slidemember mounted on said base, a grinding tool rotatably mounted on saidfirst slide member, a second slide member mounted on said base andmovable in a direction out of the plane of movement of said first lanemember, an arbor rotatably mounted on said second slide member forholding a workpiece, means operable by said motor to rotate saidgrinding tool and said arbor in timed relation, means operable by saidmotor for moving said second slide member in the direction of the axisof the arbor, and means operable by said motor for reciprocating saidfirst slide member in a direction perpendicular to the axis of the arborin timed relationship with the movement of said second slide member.

3. A machine in accordance with claim 2 wherein the means operable toreciprocate said first slide member includes a rack slidably mounted onsaid base and engageable by a revolving crank whereby said rack iscaused to reciprocate, a pinion intermeshing with said rack, a threadedrod on which said pinion is secured, and means on said first slidemember for threadably engaging said threaded rod.

4. In a machine of the type described, a base, a motor, a first slidemounted on said base for rotatably supporting a grinding tool, a headframe having a circular spigot portion at one end thereof adapted tosnugly fit in a circular recess provided in said base, a second slideslidably mounted on said head frame for rotatably supporting aworkpiece, said second slide being movable in a direction out of theplane of movement of said first slide, means to drive said first andsaid second slides reciprocably in timed relationship, means operable bysaid motor to rotatably drive said grinding tool, and means operable bysaid motor to rotatably drive the workpiece in timed relation to therotation of said grinding tool, said last-named means including arotatable shaft extending centrally through the recess of said base andthe spigot portion of said head frame, said shaft having a gear at oneend thereof drivably connected to the workpiece.

S. in a grinding machine of the type described, means rotatably tosupport a helical-profile grinding tool, means for rotatably supportinga workpiece with its axis perpendicular to the axis of said tool, meansfor rotatably driving said grinding tool and the workpiece in timedrelation, means to reciprocate said workpiece axially, and means toreciprocate said grinding tool with respect to said workpieceperpendicularly to the axis thereof and in timed relation to the axialtravel of said workpiece.

6. The invention according to claim 5 wherein said last-named meansincludes a rack, means to reciprocate said rack in timed relationship tothe axial movement or said workpiece, and a pinion engaging said rack,said pinion being geared to a threaded member that engages one of saidsupporting means.

7. The invention according to claim 5 wherein the grinding toolsupporting means is a slide member reciprocable upon a base membertowards and away from the workpiece.

The invention according to claim 6 wherein said rack is provided with aslot at one end thereof extending transversely to the line of the rackand is reciprocated upon rotation of a rotatable member by a crank pinmounted upon said rotatable member and extending into said slot.

9. The invention according to claim 8 in which said crank pin isadjustably mounted on said rotatable memher and is fixable at varyingdistances from the axis of rotation thereof.

References Cited in the file of this patent UNITED STATES PATENTS1,693,781 Hanson Dec. 4, 1928 2,307,238 Ross Jan. 5, 1943 2,360,235Jellis Oct. 10, 1944 2,385,650 Rickenmann Sept. 25, 1945 2,424,191Rickenmann July 15, 1947 2,443,410 Wickman June 15, 1948 2,482,800 RossSept. 27, 1949 2,597,648 Lucas May 20, 1952 2,620,599 Riley Dec. 9, 19522,642,702 Staples June 23, 1953 FOREIGN PATENTS 664,539 Great BritainJan. 9, 1952

